Dissident shareholders are pressing once more for media mogul Rupert Murdoch to step down as chairman of News Corporation.

Shareholders from the US, UK and Canada filed a resolution on Tuesday calling for News Corp to appoint an independent chairman. A similar resolution attracted strong support at the media company's annual shareholder meeting last year.

The proposal was introduced by Christian Brothers Investment Services (CBIS), which manages $4.6bn for Catholic institutions worldwide. It is backed by the UK's Local Authority Pension Fund Forum, with assets of £115bn ($178.9bn), and British Columbia Investment Management Corporation, one of Canada's largest institutional investors.

In a separate resolution Nathan Cummings Foundation, an ethical investment group, has called on News Corp to end the dual class share structure that allows the Murdoch family to control its media empire despite owning a minority of shares.

"A resolution introduced at last year's meeting which called for an independent chairman was approved by two-thirds of the independent shareholders, while another calling for the elimination of the company's dual-class share structure was approved by 62% of the public shareholders," CBIS said in a statement.

"The shareholders believe that by responding positively to these corporate governance issues, News Corporation can improve oversight of management, reduce business risk and better represent the interests of all shareholders. These two resolutions are the latest salvos in an ongoing campaign by concerned institutional investors to dramatically revise the corporate governance practices at News Corporation," it said.

Pressure for change from shareholders has been mounting since the phone-hacking scandal at News Corp's UK newspapers triggered investigations on both sides of the Atlantic. The company announced last year that it is intending to split its publishing assets, including the Wall Street Journal, Dow Jones and Times newspapers, from its faster growing TV and film assets. Murdoch plans to be chairman of both companies.

News Corp is expected to give an update on that split when it releases its latest quarterly results in New York later on Wednesday.